1. Technical Field
The present invention relates to a wiring substrate, droplet ejection head, printing apparatus, electronic device, and manufacturing method for the wiring substrate.
2. Related Art
Printing apparatuses are commonly used to eject droplets of liquid from an ejection head to perform a printing process on a recording medium, such as a printing sheet. One example of one such printing apparatus including the droplet ejection head is disclosed in JP-A-2006-289943 (Patent Literature 1). As is described in Patent Literature 1, the droplet ejection head includes a cavity that stores ink and a channel forming substrate including an ejection port that communicates with the cavity and ejects the ink in the cavity as droplets. A piezoelectric element is arranged adjacent to the cavity. The piezoelectric element is electrically connected to, via a wire, a driver IC that controls driving of the piezoelectric element. The driver IC drives the piezoelectric element to thereby cause the piezoelectric element to eject ink droplets from the ejection port.
A reservoir substrate is bonded and fixed to the droplet ejection head to be superimposed on the channel forming substrate. A semiconductor integrated circuit such as a driver IC is set on the reservoir substrate. Wires are set from the semiconductor integrated circuit to the piezoelectric element.
A slope is formed on the reservoir substrate. A plurality of wires are set between the slope and the channel forming substrate. A film of an adhesive is present between the reservoir substrate and the channel forming substrate. Wires are also set on the film of the adhesive. An organic matter is included in the adhesive. When wires are set in places that where the wires are in contact with the organic matter, migration easily occurs among the wires. Consequently, there is a risk that a short circuit may occur among the wires. Therefore, there is a demand for a droplet ejection head including a wiring substrate that can suppress occurrence of migration and prevent a short circuit among the wires.